Feature: #89171 - Added possibility to have multiple sitemaps

Description

You can now also create multiple different sitemaps. This can be handy for situations, where different target systems need them in different format or order. (e.g. Google News Sitemaps)

The syntax looks like this:

plugin.tx_seo {
   config {
      <sitemapType> {
         sitemaps {
            <unique key> {
               provider = TYPO3\CMS\Seo\XmlSitemap\RecordsXmlSitemapDataProvider
               config {
                  ...
               }
            }
         }
      }
   }
}

Example:

seo_googlenews < seo_sitemap
seo_googlenews.typeNum = 1571859552
seo_googlenews.10.sitemapType = googleNewsSitemap

plugin.tx_seo {
    config {
        xmlSitemap {
            sitemaps {
                news {
                    provider = GeorgRinger\News\Seo\NewsXmlSitemapDataProvider
                    config {
                        ...
                    }
                }
            }
        }
        googleNewsSitemap {
            sitemaps {
                news {
                    provider = GeorgRinger\News\Seo\NewsXmlSitemapDataProvider
                    config {
                        googleNews = 1
                        ...
                        template = GoogleNewsXmlSitemap.html
                    }
                }
            }
        }
    }
}

Impact

As it only gives the possibility to add multiple sitemaps, it won't affect any installation unless you add more sitemaps yourself.